It is known to weld two parts of a fastener together through a fabric support for the resulting fastener. Generally speaking, such fasteners have an array of projections on one part which are intended to pierce through the fabric and to weld, especially ultrasonically, to the other part.
The projections are generally disposed in a circular array, i.e. lie along an imaginary circle centered at the center of the button or fastener.
Experience with such fasteners has shown that improvement is required in attachment of the two parts of the fastener together.